Art of producing permanent magnets



Patented July 17, 1928.

UNITED. STATES .PATENT OFFICE.

LESLIE E. HOWARD AND ALLEN D. POTTS, OF LOCKPORT, NEW YORK, ASSIGNORS TO SIMONDS SAW AND STEEL COMPANY,

rom'rion or MASSACHUSETTS.

No. Drawing.

This invention relates to permanent magnets and to a method for making the same.

In the art of making magnets, it has long been a. matter of common knowledge that carbon steels which have been heated and then quenched thereby acquire the property of retaining a considerable proportion of any magnetic flux or magnetization which may be subsequently induced in them by the application of exterior forces.

Certain of the alloy steels, such as tungsten-, chrome-, chrome-tungsten-steels, and the like, also manifest per se, this property of retaining an impressed magnetic flux, more permanently and in a greater proportion than do the straight carbon steels.

In the commercial production of magnets,

however, it is usually necessary that they conform to certain shapes and sizes in order .to adequately serve the several purposes for which they may be intended. This requires either that the metalbe heated ands'haped while hot (as by forming under a drop hammer or the like) or that the metahbe given a preliminary annealing or reheating treatment and then shaped, when cold stamping or bending operations are to be carried out.

Such heating and cooling or annealing of either carbon or alloy steels (and especially of tungsten alloy steels) tends to greatly reduce the degree or proportional amount of residual magnetization which the 'metal is capableof acqulrlng or retain ng under demagnetizing influences.

For example, if the metal is shaped without any heating whatever and, after forming,

is heated to the proper temperature and hardened by quenching, it will always be superior in its magnetic qualities and properties to one which has been, for instance, annealed or heated in the forming operation and allowed to cool more or less slowly. In other words, subsequent hardening of the steel is inadequate to overcome the efi'ects of previous heat treatments, such as annealing, or to..restore the capacity or magnetic quality ofthe alloy for acquiring a permanent magnetization. This deterioration of magnetic. quality by heat is more apparent with the alloy steels than with straight carbon steels, and is especially marked with the tungsten-steels which are otherwise characterized by manifesting a particularly high capacity for retaining residual magnetisim OF FITCHBURG, MASSACHUSETTS, A. COR- ART OF PRODUCING PERMANENT MAGNETS.

Application filed October 9, 1926. Serial No. 140,671; c

Accordingly it is an object of the present inventlon to provide a magnet steel which may be shaped, annealed, bent, and other for makingpermanent magnets therefrom.

Other objects of the invention will appear from the preceding and following disclosure, and from the claims.

The present invention includes .the discovery that the addition or presence of vanadium in steel renders the resulting compound or alloy not only susceptible of initially retaining a high degree of residual magnetization (proportionate, for example, to the impressed magnetic flux to which it may be subjected), but also capable of retaining such magnetic quality in spite of annealing or other heat treatmentand the effects of mechanical working and manipulation of the metal before final hardening. A still further discovery, forming a part of the present invention, is that such improvement of the qualities of magnetization and permanency are manifested to a greater degree with the magnetic alloy steels and more particularly with those alloy steels which are subject to the inhibitions above noted, namely, steels containing tungsten.

The invention will accordingly be described, with reference to its application'to tungsten alloy steels, butit is to be underquenching) and finally magnetized in the usual way. v

Such additions of vanadium to steel result in producing a more stable condition of the resulting metal or alloy, with corresponding freedom from the troubles and difiiculties incident to or resulting from the annealing, heating and forming operations which have been alluded to above. A proportion of to 1.00% of vanadium constitutes a preferred range for magnets having such shapes as to require usual heat treatment for shaping purposes.

This preservation of the magnetic quality of the steel permits of permanent magnets being successfully fashioned while hot or annealed to facilitate punching, drilling,

tapping of holes and other like operations in the cold without lowering their capacity for subsequent acquisition of permanent magnetism.

Vhile the invention has been more particularly described with reference to its adaptation to tungsten steel, it is to be understood that like results may be attained with carbon steels and other alloy steels such as chrome steel, chrome-tungsten steel and the like. Other modifications and adaptations of the invention may and ordinarily will be resorted to in the practical application of the same for commercial operations and uses, but such modifications and adaptations are to be considered as 00111- prehended by the above disclosure and included within the terms of the following claims. I

\Ve claim:

1. An alloy steel containing vanadium in quantity sufficient to permit the steel to be reheated and shaped without destroying its magnetic quality and characterized by a.

substantially permanent magnetization. v

2. A permanent magnet comprlsing steel having a vanadium content of .05 to 1.00%, reheated and shaped to the desired form, hardened and magnetized.

3.-A permanent magnet comprising a tungsten steel having a vanadium content of .05 to 1.00%, and characterized by a substantially permanent magnetization.

Cignedby us at Lockport, New York, this 5th day of'October, 1926.

LESLIE E. HOlVARD. ALLEN D. POTTS. 

